The disclosure relates to energy assisted magnetic recording transducers or hard disk drives.
A conventional heat assisted magnetic recording (HAMR) transducer is used in writing data to a recording media. The conventional HAMR receives light, or energy, from a conventional laser, which may be a diode laser, for example. The current areal data density using HAMR is about 1 Tb/in−2. The HAMR is conventionally bonded to a slider that rides on an air bearing surface of the recording media. The slider is attached to an arm that rotates to provide the slider and HAMR access to write tracks on the media at different radii.
The surface plasmon effect may be applied in a near-field transducer (NFT) to write data bits of smaller dimension than with conventional HAMR, on the order of 70 nm or less, but with higher heat energy density, increasing the possible areal data density that may be written to a magnetic disk. It is estimated that areal densities approaching 3 Tb/in−2 are possible.
The NFT is effective in heating high magnetic anisotropy materials for about 1 nsec above the phase transition temperature to briefly lower the high coercivity, enabling the write head to record data that becomes stable once the heated bit region cools to ambient. The small size of the data bit translates into a large increase of storage density as compared to current areal densities of about 1 Tbm−2.
However, because of the intensity of the resonant electromagnetic field that builds up in the NFT, the accumulated heat concentration may cause migration of the NFT material, thereby degrading the effectiveness of a HAMR. In-process anneals and better alloys have been proposed to mitigate this problem but studies indicate the need for anneals at greater than 200° C. However the disk reader and hard baked photoresist structures of the hard disk drive may degrade for >200° C. Local heating with a laser spot has been proposed but may not be economic and readily reduced to practice. Therefore a local annealing technique is needed.